1. Field of the Invention
The present invention relates generally to an air induction system for a multi-cylinder engine and, more particularly, to an improved air induction system for a multi-cylinder engine that includes an auxiliary air supply arrangement.
2. Description of Related Art
Multi-cylinder engines can have air induction systems that include multiple air intake passages through which air can be introduced into a set combustion chambers. Each intake passage is provided with a throttle valve that regulates an amount of air provided to the engine (i.e., controls the airflow rate) and is operable with an appropriate throttle linkage. The induction system thus can supply a desired amount of air to the combustion chambers based upon the throttle opening degree, which corresponds to operator demand on engine output.
In most engine technologies, an idle condition exists when the engine maintains a certain preset engine speed with substantially no applied engine load. Typically, the throttle valves are held in an almost closed position during idling. In some engine configurations, auxiliary intake passages are provided to bypass the throttle valves so that a certain preset amount of air can be supplied to the combustion chambers even though the throttle valves are substantially closed during idling. U.S. Pat. No. 6,015,319 discloses an improved air induction system that includes such auxiliary intake passages. The auxiliary intake passages can be used for other purposes, as well. For instance, during sudden deceleration, the throttle valves generally would be abruptly closed and such an abrupt closure may invite engine stall. An additional amount of air can be supplied through the auxiliary passages to reduce the likelihood of engine stall. In some situations, the engine also may need supplemental air during rapid acceleration. This supplemental air can also be supplied through the auxiliary passages.
Typically, each auxiliary passage has a relatively small diameter. The restricted diameter may result in a delayed flow of the supplemental air due to internal flow resistance. In other words, the desired amount of supplemental air may not be timely supplied. Nevertheless, broadening the passages is contrary to the desire to minimize engine component sizes to reduce overall engine compartment size. JP 2000-130262 discloses a common chamber that is defined by unifying the auxiliary intake passages. The common chamber can improve the situation to a certain extent. However, the delayed air flow still occurs to an unacceptable degree.
A need therefore exists for an improved air induction system for a multi-cylinder engine that can supply supplemental air through auxiliary passages without significantly delaying the air flow when the need for the air arises.
The auxiliary intake passages can also include a control device that controls an amount of the air passing through the auxiliary passages. Typically, the device includes a control valve that is controlled by an electronic control unit (ECU). JP 2000-130262 also discloses a control device disposed on a member that at least partially defines the common chamber. As disclosed therein, the unitary mechanism that includes the control device and the common chamber is mounted in a location on the engine that can accommodate the unitary mechanism. The space, however, generally is relatively far from the primary intake passages. Thus, the length of the auxiliary passages is increased and the flow resistance, therefore, also increases.
Another need thus exists for an improved air induction system for a multi-cylinder engine that can provide an appropriate arrangement in which flow resistance of air that passes through the auxiliary intake passages does not substantially increase due to the provision of a control device that controls an amount of air passing though the auxiliary passages.
In accordance with one aspect of the present invention, an internal combustion engine comprises an engine body. A plurality of moveable members are moveable relative to the engine body. The engine body and the moveable members together define a plurality of combustion chambers. An air induction system is arranged to introduce air into the combustion chambers. The air induction system includes first intake passages through which the air at least in part flows to the combustion chambers. At least one valve is arranged to regulate an amount of the air flowing through the first intake passages. Second intake passages are provided through which the air at least in part flows to the combustion chambers. Each one of the second intake passages communicates with each one of the first intake passages at a location positioned downstream of the first valve. The second intake passages are unified with each other to form a unified portion. The unified portion at least in part defines a common chamber and an air inlet. The common chamber is positioned closer to the location communicating with the first intake passages than the air inlet.
In accordance with another aspect of the present invention, an internal combustion engine comprises an engine body. A plurality of moveable members are moveable relative to the engine body. The engine body and the moveable members together define a plurality of combustion chambers. An air induction system is arranged to introduce air into the combustion chambers. The air induction system includes primary passages through which first part of the air flows to the combustion chambers. At least one valve is arranged to regulate an amount of the air flowing through the primary passages. First auxiliary passages each communicates with each one of the primary passages at a location positioned downstream of the valve. The first auxiliary passages are unified with each other to form a common chamber. A second auxiliary passage has a first end communicating with the common chamber and a second end communicating with a location in the atmosphere. Second part of the air flows to the combustion chambers through the first and second auxiliary passages and the common chamber. The common chamber is positioned next to the primary passages.
In accordance with a further aspect of the present invention, an internal combustion engine comprises an engine body. A plurality of moveable members are moveable relative to the engine body. The engine body and the moveable members together define a plurality of combustion chambers. An air induction system is arranged to introduce air into the combustion chambers. The air induction system includes intake passages through which first part of the air flows to the combustion chambers. At least one first valve is arranged to regulate an amount of the first part of the air. Multiple secondary passages each communicates with each one of the intake passages at a location positioned downstream of the first valve. The multiple secondary passages are unified with each other to form a common chamber. A single secondary passage has a first end communicating with the common chamber and a second end communicating with a location in the atmosphere. Second part of the air flows to the combustion chambers through the single and multiple secondary passages and the common chamber. A second valve is arranged to control an amount of the second part of the air. The second valve is positioned in the single secondary passage apart from the common chamber.